Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for performing service-specific access control in a wireless communication system.
Related Art
Universal mobile telecommunications system (UMTS) is a 3rd generation (3G) asynchronous mobile communication system operating in wideband code division multiple access (WCDMA) based on European systems, global system for mobile communications (GSM) and general packet radio services (GPRS). A long-term evolution (LTE) of UMTS is under discussion by the 3rd generation partnership project (3GPP) that standardized UMTS.
IP multimedia subsystem (IMS) multimedia telephony service (MMTel) is a global standard based on the IMS, offering converged, fixed and mobile real-time multimedia communication using the media capabilities such as voice, real-time video, text, file transfer and sharing of pictures, audio and video clips. With MMTel, users have the capability to add and drop media during a session. It is possible that chat, add voice (for instance mobile VoIP), add another caller, add video, share media and transfer files, and drop any of these can begin without losing or having to end the session.
In an emergency situation, like earthquake or tsunami, degradation of quality of service may be experienced. Degradation in service availability and performance can be accepted in such situations, but mechanisms are desirable to minimize such degradation and maximize the efficiency of the remaining resources. When domain specific access control (DSAC) mechanism was introduced for UMTS, the original motivation was to enable packet-switched (PS) service continuation during congestion in circuit switched (CS) nodes in the case of major disaster like an earthquake or a tsunami. In fact, the use case of DSAC in real UMTS deployment situation has been to apply access control separately on different types of services, such as voice and other PS services. For example, people's psychological behavior is to make a voice call in emergency situations and it is not likely to change. Hence, a mechanism will be needed to separately restrict voice calls and other services.
As an evolved packet system (EPS) is a PS-domain only system, the DSAC does not apply. Therefore, service-specific access control (SSAC) may be applied instead of DSAC. Considering the characteristics of voice and non-voice calls in EPS, requirements of the SSAC could be to restrict the voice calls and non-voice calls separately.
For a normal paid service there are quality of service (QoS) requirements. The provider can choose to shut down the service if the requirements cannot be met. In an emergency situation, the most important thing is to keep communication channels uninterrupted, therefore the provider should preferably allow for a best effort (degradation of) service in preference to shutting the service down. During an emergency situation, there should be a possibility for the service provider also to grant services, give extended credit to subscribers with accounts running empty. Under some circumstances, overload access control may be invoked giving access only to authorities or a predefined set of users.
A method for performing SSAC efficiently may be required.